1. Field of the Invention
The present invention relates to a suspension that is capable of preventing vibration or shock generated from a road surface from being directly transmitted to a car body, thereby improving ride comport, and more particularly to a suspension that allows adjustment of a forward/backward tilt angle of a strut from a line perpendicular to a road surface, whereby a caster angle is easily changed. Also, the present invention relates to an insulator of the same.
2. Description of the Related Art
FIGS. 1 to 4 show a front wheel suspension and its insulator.
The suspension as shown in FIGS. 1 to 4 comprises: a strut 10 integrally attached to a steering knuckle 4, which is a center of a front wheel 2, by means of a king pin 6 while being disposed in parallel with a center line 7 of the king pin 6; an insulator 12 connected to the strut 10 and attached to a car body by means of bolts 11 for absorbing vibration or shock transmitted from the front wheel 2; a suspension spring 14 disposed on the outer circumference of the upper part of the strut 10 for relieving shock transmitted from a road surface; and a shock absorber 16 mounted to the strut 10 for restraining free vibration of the suspension spring 14 to improve ride comfort.
The strut 10 is moved forward and backward or right and left along with the steering knuckle 4 about the king pin 6, by which four factors for aligning the front wheel 2, such as a camber angle, toe-in, a caster angle θ, and a king pin tilt angle, are determined.
Referring to FIG. 4, the caster angle θ is an angle between the center line 7 of the king pin 6 and a vertical line 8 perpendicular to the road surface when the front wheel 2 is seen from the side. In other words, the caster angle θ is a forward/backward tilt angle of the strut 10 from the vertical line 8 perpendicular to the road surface.
As the caster angle θ is increased, the distance between a caster point 20 where the extension of the center line 7 of the king pin 6 crosses the road surface and the center 22 of the road surface where the front wheel 2 contacts is also increased. As a result, a restoring force for guiding the front wheel 2 in the traveling direction of a vehicle is increased. However, the steering operation is very difficult.
The positions where the struts are assembled are different according to kinds of vehicles since required optimal caster angles are different according to kinds of vehicles, and required optimal caster angles are different depending on whether a power steering system to increase the steering forces of drivers of the vehicles is included or not although the kinds of vehicles are the same. Consequently, the conventional suspension and its insulator have low compatibility with the result that the suspension and its insulator suitable for one kind of vehicle are not adequately adopted in other kinds of vehicles. Although the conventional suspension and its insulator is adopted in the same kind of vehicles, it may be difficult to obtain an optimal caster angle depending on whether an optional accessory, such as a power steering system, is included or not.
Furthermore, it is difficult to change the caster angle once the caster angle is initially determined in any kind of vehicle.